Upgrade to 3.1: it keeps asking the database to be updated (15 posts)

Hi,
after having upgraded from 3.0.2 to 3.1, it keeps asking:
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Database Update Required
WordPress has been updated! Before we send you on your way, we have to update your database to the newest version.
The update process may take a little while, so please be patient.
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THEN:
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Update Complete
Your WordPress database has been successfully updated!
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The blog itself is working (http://www.albertoboccalatte.it/blog/) but it keeps asking for a database update if I log in into administration panel, so I can't write new posts or do anything.

Try:
- switching to the Twenty Ten theme by renaming your current theme's folder in wp-content/themes using FTP or whatever file management application your host provides. You may need to try logging into your site to get this to kick in fully.